/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.fs;



import com.google.auto.value.AutoValue;

import com.bff.gaia.unified.sdk.annotations.Experimental;

import com.bff.gaia.unified.sdk.io.FileSystems;

import com.bff.gaia.unified.sdk.io.FileSystem;



import java.io.File;

import java.io.IOException;

import java.io.Serializable;

import java.util.List;



/** The result of {@link FileSystem#match}. */

public abstract class MatchResult {



  private MatchResult() {}



  /** Returns a {@link MatchResult} given the {@link Status} and {@link Metadata}. */

  public static MatchResult create(Status status, List<Metadata> metadata) {

    return new AutoValue_MatchResult_Success(status, metadata);

  }



  @AutoValue

  abstract static class Success extends MatchResult {

    abstract List<Metadata> getMetadata();



    @Override

    public List<Metadata> metadata() throws IOException {

      return getMetadata();

    }

  }



  /** Returns a {@link MatchResult} given the {@link Status} and {@link IOException}. */

  public static MatchResult create(final Status status, final IOException e) {

    return new AutoValue_MatchResult_Failure(status, e);

  }



  @AutoValue

  abstract static class Failure extends MatchResult {

    abstract IOException getException();



    @Override

    public List<Metadata> metadata() throws IOException {

      throw getException();

    }

  }



  /** Returns a {@link MatchResult} with {@link Status#UNKNOWN}. */

  public static MatchResult unknown() {

    return new AutoValue_MatchResult_Failure(

        Status.UNKNOWN,

        new IOException("MatchResult status is UNKNOWN, and metadata is not available."));

  }



  /** Status of the {@link MatchResult}. */

  public abstract Status status();



  /**

   * {@link Metadata} of matched files. Note that if {@link #status()} is {@link Status#NOT_FOUND},

   * this may either throw a {@link java.io.FileNotFoundException} or return an empty list,

   * depending on the {@link EmptyMatchTreatment} used in the {@link FileSystems#match} call.

   */

  public abstract List<Metadata> metadata() throws IOException;



  /** {@link Metadata} of a matched file. */

  @AutoValue

  public abstract static class Metadata implements Serializable {

    private static final long UNKNOWN_LAST_MODIFIED_MILLIS = 0L;



    public abstract ResourceId resourceId();



    public abstract long sizeBytes();



    public abstract boolean isReadSeekEfficient();



    /**

     * Last modification timestamp in milliseconds since Unix epoch.

     *

     * <p>Note that this field is not encoded with the default {@link MetadataCoder} due to a need

     * for compatibility with previous versions of the Unified SDK. If you want to rely on {@code

     * lastModifiedMillis} values, be sure to explicitly set the coder to {@link MetadataCoderV2}.

     * Otherwise, all instances will have the default value of 0, consistent with the behavior of

     * {@link File#lastModified()}.

     *

     * <p>The following example sets the coder explicitly and accesses {@code lastModifiedMillis} to

     * set record timestamps:

     *

     * <pre>{@code

     * PCollection<Metadata> metadataWithTimestamp = p

     *     .apply(FileIO.match().filepattern("hdfs://path/to/*.gz"))

     *     .setCoder(MetadataCoderV2.of())

     *     .apply(WithTimestamps.of(metadata -> new Instant(metadata.lastModifiedMillis())));

     * }</pre>

     */

    @Experimental

    public abstract long lastModifiedMillis();



    public static Builder builder() {

      return new AutoValue_MatchResult_Metadata.Builder()

          .setLastModifiedMillis(UNKNOWN_LAST_MODIFIED_MILLIS);

    }



    /** Builder class for {@link Metadata}. */

    @AutoValue.Builder

    public abstract static class Builder {

      public abstract Builder setResourceId(ResourceId value);



      public abstract Builder setSizeBytes(long value);



      public abstract Builder setIsReadSeekEfficient(boolean value);



      public abstract Builder setLastModifiedMillis(long value);



      public abstract Metadata build();

    }

  }



  /** Status of a {@link MatchResult}. */

  public enum Status {

    UNKNOWN,

    OK,

    NOT_FOUND,

    ERROR,

  }

}